Hydraulic starting motor



A. c. JENNY I 2,711,724

HYDRAULIC STARTING MOTOR June 28, 1955 3 Sheets-Sheet l Filed Aug. 2, 1952 wi l] ENTOR. ALBERT C. q- JENNY ATTORNEY June 28, 1955 A. c. JENNY 2,711,724

' HYDRAULIC STARTING MOTOR Filed Aug. 2, 1952 3 Sheets-Sheet 2 FIG. 4

IN V EN TOR.

ALBERT c. JENNY ATTORNEY June 28, 1955 Filed Aug. 2, 1952 A. C. JENNY HYDRAULIC STARTING MOTOR 3 Sheets-Sheet 3 INVENTOR. ALBERT c. JENNY ATTORNEY Patented June 28, 19555 lice HYDRAULlC STARTENG MOTOR Albert C. Jenny, Cleveland, Ohio, assignor, by mesne assignments, of one-third to William W. Lytle, one-third to Albert C. Jenny, and one third to C. Grief Raible.

Application August 2, 1952, Serial No. 392,363

6 Claims. (Cl. 123-179) This invention pertains to the art of fluid-translating devices and, more particularly, to fluid motors or pumps of the rotating cylinder or swash-plate type.

The invention is particularly adapted for use in hydraulic starting motors and will be described with particular reference thereto, although it will be appreciated that the invention is likewise useable with air or other forms of motors as well as hydraulic pumps.

Hydraulic motors of the type to which this invention particularly pertains normally include a rotatable cylinder barrel having a plurality of pistons reciprocably mounted therein on lines of movement parallel to and spaced around the axis of rotation of the cylinder barrel, the pistons bearing at one end against an angularly positioned thrust or swash plate disposed generally coaxial about the axis of rotation. The swash plate is ordinarily in the form of a roller thrust bearing. These motors may be used with hydraulic-fluid pressures varying anywhere from 500 to 5000 pounds per square inch and are capable of delivering high torques at high rotational speeds.

In such motors, the mechanical forces involved are usually very high, the mechanical clearances very low and because of the high pressure, the friction losses tend to be excessive. Much of this friction loss is due to the rubbing of the nose of the piston on the bearing surface of the swash plate, which rubbing normally occurs even though a roller thrust bearing for the swash plate is employed.

Further, in such motors, because of the high pressures involved, there is always a tendency to have a slight leakage of the hydraulic fluid past the piston and past the valve-sealing surfaces into the interior of the motor creating a high pressure within the motor and seriously impeding the operation thereof and, particularly, the chiciencyv This fluid interferes with both the proper reciprocation of the pistons and with the operation of the balls of the ballbearing and is churned into a foam or froth as well as being overheated from the churning action.

The elimination of the leakage pressure has always been a problem. If it is Vented directly to atmosphere, it is messy. Also, the vent provides a possible source of entry for dirt into the motor itself.

As indicated, hydraulic starting motors possess the features of an extremely high torque, rapid acceleration to the rotational speed and a relatively high speed of rotation. If these hydraulic motors are used for starting motors for large pieces of industrial apparatus, such as diesel internal-combustion engines, they must be provided with a gear to mesh at desired intervals with a corresponding gear on the apparatus. Because of the features just referred to, difficulty has been experienced with a tendency to breakage or excessive wear of the gear teeth due, as it has now been determined, to failure of properly synchronizing the meshing of the gear teeth with the application of hydraulic pressure to the motor to operate it.

The present invention contemplates and has for its object a fluid-translating device of the rotating cylinder swash-plate type which adequately provides for and overcomes all the above-mentioned difficulties as well as others, and generally include a housing, a rotatable cylinder barrel in the housing having a plurality of pis tons reciprocable therein on lines of movement paralle to and equally spaced around the axis of rotation, and a swash plate against which the ends of the pistons bear so as to be reciprocated as the cylinder barrel rotates, the piston diameter and shape being all so inter-related with the angle and position of the swash plate as to have a minimum of friction and wear. The pistons have the end bearing against the swash plate rounded with the radius of curvature generally equal to one-half the diameter of the pistons, together with the angle of the swash plate being such as to make the stroke of the pistons equal to the diameter thereof.

The invention also contemplates having the swash plate formed with a rotatable member, the center of rotation of which is on a line intersecting the axis of rotation of the cylinder barrel with the plane through the centers of curvature of the piston ends.

Alternatively, the piston ends may have balls or spheres rotatably supported thereon for bearing against a fixed thrust or swash plate, the sockets for the balls communicating with the source of hydraulic fluid so as to be lubricated thereby.

The invention further contemplates a fluid-translating device of the type described wherein the exhaust or discharge port for the cylinders is so constructed and arranged with passages to the interior of the motor as to provide a venturi or suction effect to positively draw off from the interior of the motor chamber any hydraulic fluid which may have leaked past the pistons or the valve seats.

The invention also contemplates a fluid-translating device of the type described operating in conjunction with a pinion gear intended to be selectively engaged with a large gear on other forms of apparatus, the assembly including means for first engaging the pinion gear and, subsequently, in the same movement, opening. a valve to admit hydraulic fluid to the motor for the purpose of rotating the pinion gear, the valve means being so constructed and arranged so as to be self balanced against the hydraulic pressures and so as to admit progressively larger amounts of hydraulic fluid as the pinion gear approaches its full meshing with its driven gear.

The invention has for its primary object the provision of a fluid-translating device of the swash-plate type which is relatively economical to manufacture, which will have a maximum of conversion of hydraulic energy to mechanical energy, which will have a minimum of wear throughout its life and which provides a maximum ease of operation.

Another object of the invention is the provision in apparatus of the type described of a new and improved relationship between the rotatable member of the swash plate, the plane containing the centers of curvature of the piston ends and the axis of rotation of the motor itself wherein reduced wear and reduced friction will result.

Another object is to provide a motor of the type referred to having pistons with spherical ends.

Another object of the invention is the provision of a new and improved arrangement for exhausting leakage fluid from the inside of the motor chamber wherein the discharge or exhaust passage of the motor is so arranged in conjunction with a vent to the interior of the motor chamber to provide a venturi effect for continuously exhausting such leakage fluid.

Still another object of the invention is the provision of new and improved means for synchronising the engagement of the pinion gear with its driven gear and the admission of hydraulic pressure to the motor.

Still another object is the provision, in a hydraulic starting motor having a mechanically engageable pinion gear, of valve mechanism on the motor so arranged as to be operated in synchronism with and by the pinion-actuating lever.

The invention may be comprised and take physical form in certain parts and combination of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawing which is a part hereof, and wherein:

Figure 1 is a side cross-sectional view of a fluidtranslating device of the swash-plate type in the form of a hydraulic starting motor embodying the present invention, the driven gear of the apparatus to be started shown fragmentally in approximately its operative relationship to the motor;

Figure 2 is an end view of Figure 1;

Figure 3 is a cross-sectional view of Figure 1 taken approximately on the line 3-3 thereof;

Figure 4 is a cross-sectional view of Figure 1 taken approximately on the line 44 thereof;

Figure 5 is a fragmentary view somewhat similar to Figure 1 showing an alternative construction for the piston and swash plate; and

Figure 6 is an end view of the piston of Figure 5 with the steel ball removed therefrom.

Referring now to the drawings wherein the showings are for the purposes of illustration only and not for the purposes of limitation, Figure 1 shows a fluid-translating device of the swash-plate type in the form of a hydraulic motor and includes, generally, a housing A; a motor unit B and a drive unit C, both operating on a common shaft; and a valve mechanism D interconnected with and operable at the same time as the drive unit C is operated.

The housing A is generally formed in two parts rigidly bolted together, including a body member 10 and an end plate 11, the body member 10 having a large internal cavity 12, the left end of which is covered over by the end plate 11.

A shaft 14 extends centrally through the cavity 12 and is supported for rotation in the end plate 11 by means of a suitable bearing, such as the needle hearing 15, and at the opposite end in the body member by a suitable hearing such as the ballbearing 16. An O-ring seal 17 seals the left end of the shaft 14 where it passes through the end plate 11, this seal preferably being placed between the needle bearing 15 and the cavity 12. In a like manner, a sealing ring 18 is provided on the cavity side of the bearing 16 to effectively prevent the passage of any hydraulic fluid along the shaft 14 to the bearings 15 or 16. Obviously, other forms of sealing means or rings can be provided than those shown.

The motor 3 comprises generally a cylinder block 20 positioned within the cavity 12 coaxial with the shaft 14 and rotatable therewith, a splined connection 21 being provided between these two members, thus giving a positive driving connection. The cylinder block 20 has a plurality of cylinder bores 23 extending inwardly into the cylinder block from the righthand end as viewed in Figure l and having a depth slightly less than the total length of the cylinder block. The cylinder bores 23 all have an axis parallel to the axis of rotation of the shaft 14 and are equi-angularly spaced around the cylinder block 20. A piston 24 is reciprocably supported in each cylinder bore 23 which pistons, in the embodiment shown, are round in shape and generally elongated so as to project beyond the right-hand end of the cylinder block 20 and this end of'the piston is formed in the shape of a sphere with the radius of curvature of the end of the piston being equal to one-half the diameter thereof for reasons which will appear hereinafter. Further, the pistons have on their external surface a plurality of circumferentially extending grooves 26 which serve to provide a sealing function to prevent or to obstruct the leakage of hydraulic fluid thereby.

The pistons 24 are preferably formed of an aluminum bronze material so as to obtain a soft lubricating action between themselves and the steel of the cylinder block 20 and any other steel parts which they engage during the course of operation of the motor.

The rounded ends of the piston 24 bear against a swash plate which, in the embodiment shown, is in the form of the movable race 28 of a ball-type thrust bear ing, the fixed race 29 of which is based in an angularly disposed recess 30 at the base of the cavity 12. The fixed race 29 and the movable race 28 are separated by a plurality of caged balls which roll in suitable grooves formed in the opposed faces of the two bearing races.

Thus, in the embodiment shown, as the cylinder block rotates, the pistons 24 which bear against the face of the race 28 are reciprocated in their cylinder bores 23 and the movable race 28 in a like manner rotates about an axis 31, the exact location of which is an important part of the invention and will be discussed hereinafter.

The base of each cylinder bore 23 has a passage 33 of somewhat smaller diameter than the diameter of the cylinder bore 23 opening to the left-hand side of the cylinder block 24), which passages register alternately as the cylinder block 20 rotates with an inlet port 34 and an outlet port 35 formed in the surface of the end piate facing the cavity 12. The surfaces of the cylin der block 20 surrounding the passages 33 and the surfaces of the end plate 11 immediately adjacent the inlet and outlet ports 34 and 35 are carefully honed and are held in pressure-sealing engagement by the action of the hydraulic pressures in the cylinder bores 23 and a helical compression spring 35 disposed around the shaft 14 and inside of the cylinder block 20, which spring, on its right-hand end, bears against a washer 37 based on a shoulder 38 on the shaft 14 and, on its lefthand end, against a washer 39 based on a split ring 40 expanded into a groove of the cylinder block 20.

To further improve the sealing action, the area of the cylinder block 20 and the end plate 11 in pressure-sealing engagement is preferably reduced by cutting away the surface of the end plate 11 as at 42. An outer bearing surface 43 is provided to take part of the pressure load of the cylinder block, this general type of reduced hearing area around the inlet and outlet passages being fully disclosed in the patent to Durner, 1,867,308 dated July 12, 1932.

The inlet port 34 and the outlet port 35 are each generally in the form of a long are corresponding to the path of rotation of the passages 33, the general extent of the are being more clearly shown by the dotted lines of Figure 2.

In the embodiment shown, the outlet port 35 opens into a chamber 45 formed internally of the end plate 11,

- which chamber, in turn, communicates externally of the end plate 11 through passages 46, 47 internally threaded to receive standard, hydraulic fittings 48. Normally, one of the openings is plugged while the other opening has a hose or tube 49 associated therewith to carry away the discharge from the motor to a suitable fluid reservoir not shown.

In a like manner, the inlet port 34 communicates with an enlarged chamber 50 formed internally of the end plate 11. This chamber 50 communicates through a vertically extending passage 51 in the end plate 11 with a horizontally extending passage 52 in the body 10 at the upper side thereof which, in turn, communicates with a chamber 53 in the body 10 forming the outlet chamber for the valve mechanism D to be subsequently described.

The chamber 50 also communicates externally of the end plate 11 through an opening or passage 54 internally threaded to receive standard, hydraulic fittings. With the construction shown, it is possible to feed hydraulic fluid to the motor either through the valve mechanism D or through the passage 54 as may be desired. If it is desired to feed hydraulic fluid to the motor only through the valve mechanism D, then the passage 54 may be suitably plugged or entirely eliminated.

The fluid-translating device shown as a preferred embodiment is primarily intended as a starting motor for large pieces of mechanical equipment, such as internalcombustion engines of the diesel type. Suchequipment, not shown, normally includes a large bull or starting gear shown in its normal relationship to the starting motor and adapted to be selectively engaged by a driving pinion 61 slidably supported but keyed to an extension of the shaft 14 from the right-hand end of the body member 16 and rotatably supported at its extreme right-hand end by means of a needle bearing 62 supported in a cap 63 forming an extension to the right of the body member 16. The driving pinion 61 is driven through an overrunning clutch arrangement 64, which forms no part of the present invention, it being similar to that shown in the patent to D. L. Miller, 2,500,132, and it is engaged by means of a collar 65 rotatable with the shaft 14 and axially slidable therealong to move the pinion 61 into engagement with the driven gear 60. The collar 65 is mechanically and forceably moved along the shaft 14 by means of a bell crank lever 66 pivoted on an axis at right angles to the axis of the shaft 14 and slightly thereabove and having a pair of yoke arms 67 extending into the groove of the collar 65.

The pinion gear 61 is shown in solid lines in its normally disengaged position relative to the gear 60. It will be noted that there is a slight spacing between the opposed faces of these gears. Movement of the bell crank lever 66 to the left, however, will fully engage the pinion 61 with its driven gear 60.

In accordance with the invention, the valve mechanism D is operated in conjunction with and in synchronization with the movements of the pinion 61 into driving engagement with the driven gear 60. Thus, the valve mechanism D is so positioned and arranged in relation to the bell crank 66 as to be operated thereby. In the embodiment shown, the valve mechanism D comprises a fixed or stationary portion 72 which is preferably formed integral with the body member 16, although it will be appreciated that the stationary portion 72 could be separate therefrom and bolted to the body member 16. The valve mechanism D includes the previously referred to outlet chamber 53. and an inlet chamber 75 to the right of the outlet chamber 53, which inlet chamber communicates with the exterior of the body 10 through a port or passage 76 internally threaded to receive a suitable hydraulic fitting. A third chamber 77 is disposed on the opposite side of the outlet chamber 53 and the three chambers are all in longitudinal alignment. This lastmentioned chamber 77 is, as shown, partially formed in the end plate 11 and has a bleed opening 77 to atmosphere. A cylindrical opening 78 extends from the righthand side of the body member 16 in parallel relationship to the axis of rotation of the shaft 14 and intercommunicates the inlet chamber 75, the outlet chamber 53 and the auxiliary chamber 77. A valve member 79 is reciprocably supported in the bore 78 and extends from the right-hand side of the body member 16 through the inlet chamber 75, the outlet chamber 53 and into the auxiliary chamber 77. A compression coil spring 30 hearing at its left end against the end plate 11 extends into a hollow end in the valve member 79 and continuously urges this valve member to the right. A spring snap ring 81 fits into a groove formed in the left end of the valve member 79 and coacts with the right-hand end of the chamber 77 to limit the right-hand movement of the valve member 79 under the influence of the spring 80.

The valve member 79 has a portion 83 of reduced diameter intermediate the ends thereof. This portion of reduced diameter 83 gradually tapers outwardly to the full diameter of the piston substantially as shown at 84 and 85'.

The valve member 79 is shown in its normal, unactuated position by the solid lines of Figure 1. When in this position, the reduced portion 83, together with the tapered portion 84, are all to the right of the left-hand wall of the inlet chamber 75.

An O-ring E7 is positioned in a groove in the wall of the bore 73 to the right of the tapered portion 85 and provides a sealing action to prevent leakage of highpressure hydraulic fluid longitudinally along the valve member 79 to the outside of the body member 16.

In a like manner, an O-ring 88 is provided in the groove 78 intermediate the inlet chamber 75 and the outlet chamber 53. Similarly, an O-ring 89 is positioned between the left-hand side of the outlet chamber 53 and the right-hand side of the auxiliary chamber 77. These Q-rings 87, 83, 89 are all under compression in their respective grooves and provide a sealing action to prevent lealiageof hydraulic fluid between the various chambers.

The right-hand end of the valve member 79 is slotted to form a pair of yoke arms which extend on both sidesof the bell crank lever 66 and a pin M supported on the bell crank lever 66 extends through openings 92 in the end of the valve member '79 so that as the bell crank lever 66 is actuated to engage the pinion gear 61 with its driven gear 60, the valve member 79 is also actuated. In the embodiment shown, the opening $2 is loosely fitted with the pin 91 so as to prevent binding due to the curved arc of movement of the pin 92 when the bell crank lever 66 is actuated.

Hydraulic motors of the type to which this invention pertains normally have unusually high torques, high acceleration and high rotative speeds which can cause serious damage to the gears 60 and 61 if the gears are not properly meshed in accordance with the application of the hydraulic pressures to the motor. The present invention contemplates a cooperative relationship between the engagement of the gears and the admission of the fluid pressure to the hydraulic motor wherein each can be under the control of a single operating lever. Thus, when the bell crank 66 is moved to the left, the valve member 79 moves in the same direction while the pinion 61 moves to the right. The first action occuring is the clearance between the pinion 61 and the gear 66) being taken up. With subsequent movement of the bell crank lever 66, the pinion 61 is engaged at predetermined amount with the driven gear 60 before the left-hand side of the tapered portion 84 has moved sufficiently far to the left to pass the right-hand wall of the outlet chamber 53. In this connection, the wall thickness between the chambers 53 and '75 must be proportioned relative to the desired length of movement of the pinion 61 and the length of the respective distances between the axis of rotation of the bell crank 66 to the respective members which are being moved thereby. It is preferred that the pinion 61 be approximately three quarters engaged with the driven gear 60 before the left-hand end of the tapered portion 84 reaches the right-hand wall of the outlet chamber 53. When this does occur, hydraulic fluid under pressure may flow from the inlet chamber 53 and thence to the inlet port 34 to the motor B. Further movement of the bell crank lever 66 continues to engage the pinion 61 while, at the same time, further but gradually opening the valve mechanism D to allow greater and greater amounts of hydraulic fluid to flow to the motor B.

In some instances, it is desired that a small amount of rotational movement of the pinion 61 occur either just before or as it enters into engagement with the driven gear 66 so that interference between the respective gear teeth cannot occur. In order to accomplish this, a small groove 94 is provided in the surface of the valve member 79 just to the left of the tapered portion 84 so that a small,

metered amount of fluid may flow before the tapered portion 84 reaches the outlet chamber 53 and a fuller flow of hydraulic fluid can result. The left-hand termination of this groove is adjusted in relationship to the gear and pinion spacing so as to bleed fluid through the valve before the gears mesh.

In the operation of hydraulic motors of this type, it is normally inevitable that there will be some leakage of fluid or otherwise into the cavity 12. This fluid, if it reaches a sufiicient volume, can cause serious difficulty in the operating efliciency f the motor. In accordance with the present invention, means are provided for positively evacuating or relieving any pressure or fluid which might accumulate in the cavity 12. Such means, in the preferred embodiment, make use of the discharge velocity of the hydraulic fluid through the outlet port 35 to create a region of low pressure in the chamber 45 which will serve to positively evacuate the cavity 12. Thus, in the embodiment shown, one or a plurality of openings 86 are provided in the end plate 11 extending from a point just adjacent the periphery of the cavity 12 to the intersection of the right-hand surface of the chamber 45 with the exhaust passage 35 immediately adjacent the outlet passages 46 and 47. Thus, as the hydraulic fluid flows out of the exhaust passage 35 at a high velocity and into the chamber 45 and the passages 46, 47, a venturi effect is created immediately opposite the left-hand end of the openings 96 to lower the pressure there and thereby provide a scavenging action to remove any fluid in or entering the cavity 12. diameter of the cylinder block 20 is slightly less than the inner diameter of the cavity 12 so that any fluid reaching the cavity 12 can readily flow between the cylinder block 20 and the body member to the passages 96.

Another problem in apparatus of the type to which this invention pertains has been that of frictional or rubbing forces between the end of the pistons and its swash plate caused by a radial displacement of the end relative to its swash plate. This rubbing causes excessive wear on the ends of the piston and, at the same time, generates heat and wastes power. The present invention contemplates so forming the piston ends and/or so positioning the axis of rotation of the movable bearing race 28 that a minimum amount of rubbing or wear will occur between the piston ends and the plate 28.

In the embodiment of the invention shown, the movof curvatures of all of the piston ends intersects the axis of the shaft 14 at a point 98. In accordance with the invention, the axis of rotation 31 of the movable bearing plates 28 should interesct the point 98. With such arrangement, it will be noted that the point of engagement of the spherical end of the piston 24 with the movable bearing race 23 is always at the same distance from the center of rotation of the bearing race 28 so that never will there be any radial movement, which is rubbing movement, between the piston ends and the bearing plate 28. Any movement which might occur is purely a rolling action between the piston ends and the plate 28. Also, with the arrangement shown, a slight tendency to rotate the pistons in their cylinder bores 23 results, providing, at all times, an even wearing action which aids in the prolonged life of all the parts of the device.

It will be appreciated that in order to obtain the stated relationships between the intersections of the axis 31 and the axis of rotation of the shaft 14, the depth of the angular recess of the cavity 12 must be carefully considered in relation to the thickness of the ball bearing forming the swash plate, as variations in the thickness of the ballbearing or in the depth of the groove will result in a shifting of the point of intersection of the plane through the centers of curvature of the pistons and the axis of rotation of the shaft 14.

In this respect, it will be noted that the outer For a maximum efficiency of operation, the invention contemplates so adjusting the angular position of the swash plate relative to the axis of rotation of the shaft 14 that the pistons will have a stroke substantially equal to their diameter, which relationship results in a minimum of wear and a maximum of mechanical efliciency. Thus, the angle of the swash plate relative to the axis of rotation of the shaft 14 should be so adjusted in relation to the radial spacing of the pistons from the axis of rotation that this relationship between the diameter of the pistons and their stroke will result.

A short splined connection is shown between the shaft 14 and the cylinder block which provides axial space for the spring 36. The splined connection can as readily be a keyed connection or otherwise and its length of engagement between the block and shaft 14 is considered unimportant and may be other than that shown.

In operation, the pinion gear 61 is normally held to the left and is entirely disengaged from the driven gear 69. When it is desired to actuate the device, the bell crank lever 66 is moved to the left, first simultaneously moving the valve member 79 to the left and the pinion 61 to the right and into engagement with the driven gear 60. Just prior to the engagement of the gears, 21

. small amount of hydraulic fluid passes through the port 94 from the inlet chamber 75 into the inlet chamber 53, thus causing the motor B to rotate slowly as will be presently described. Further movement of the bell crank lever 66 further engages the gears and eventually the tapered portion 84 passes into the outlet chamber 53, allowing, at first, a small amount and then, subsequently, larger amounts, as the valve member is moved further to'the left, of hydraulic fluid to flow into the outlet chamber 53. This fluid passes under pressure from the outlet chamber 53 through the passages 52 and 51 to the chamber 50 internally of the end plate 11. The fluid then passes through the inlet port 34 which, as shown, has a circumferential extent of about 135 F. Hydraulic fluid then enters the cylinder bores 23, forcing the pistons 24 against the plate 28 which, because of the angle of engagement, causes the cylinder block 20 with the pistons therein to rotate about the axis of the shaft 14, thus rotating the shaft 14 and driving the pinion gear 61. After the piston 24 has been moved to the maximum distance to the right in the cylinder bore 23, the passage 33 then moves into engagement with the outlet or exhaust passage and the hydraulic fluid in the cylinder bore 23 is discharged at a high velocity into the chamber and thence externally of the end plate 11. In this connection, it is preferred that the outlet piping have a substantially larger diameter than the inlet piping to facilitate in the discharge of the fluid, as well as to facilitate in the creation of the lower pressure area opposite the left end of the opening 96. As will be noted, the three openings 96 shown can provide a positive evacuation for the cavity 12, thus quickly removing any hydraulic fluid which might leak thereinto.

Whenever it is desired to stop the motor B, it is simply necessary to release the bell crank lever 66 and the I spring 86 pushes the valve member 79 to the right and the invention and like parts have been designated by like numerals and similar parts have been designated by like numerals with a prime mark added.

The principal difference between the embodiments shown in Figures 5 and 6 and that of the principal embodiment shown in Figures 1 to 4 is in the construction of the piston ends and the swash or thrust plate. Thus, in Figure 5, pistons 24 have a spherical socket 109 formed in their right-hand end in which a steel ball 101 is supported for free rotation in any direction. The diameter of the spherical socket 10% is just slightly less than the 9 outer diameter of the piston 24 and has a depth somewhat greater than the diameter of the ball 101 to be inserted therein, thus leaving a thin edge 162 which, after the ball 1.01 is inserted in the socket 1%, can be slightly deformed or bent over to retain the ball in the socket.

The piston 24' is hollow as is the piston 24, although the depth of the cavity 1% of the piston 24 is some;- what less than the depth of the cavity of the piston 24-. The base of the socket 1% has a small port 105 communicating the base of the socket ltltl with the cavity 104. The base of the socket filth also has several small grooves 136 communicating with the passage 105 and extending outwardly from the passage 1% in the surface of the socket 1% a short distance substantially as shown in Figure 6.

With the just described piston construction, it is possible to eliminate the ballbearing thrust or swash plate of the principal embodiment and substitute therefor a fixed thrust or swash plate 103 mounted in an angular seat 109 formed on the right-hand end of thecavity 12 of the housing 10. This plate 108 can be of a lead bronze bearing material.

In operation, the hydraulic fluid under pressure which enters the cylinders 23 forces the piston 24 against the bearing plate lti'd and causes the cylinder block to rotate similarto the operation of Figure 1. However, as the cylinder block 20 rotates, the pistons are advanced in a circumferential direction around the plate 108 and the steel ball rotates in its socket 1%, thereby giving a substantially friction-free engagement for the end of the piston 24 in relation to the swash plate ltlfi. Additionally, the hydraulic fluid under pressure can flow through the passage 135 where it will lubricate the ball 101 in its socket ltltl.

The present invention has been described with reference to a hydraulic motor. It will be appreciated that the invention is likewise applicable to pumps, in which case, compression coil springs would be inserted in each cylinder bore to continuously urge the pistons 24 to their extended position. Alternatively, the inlet port on the pump can be supercharged by one means or another, all well known in the art.

The present valve design, in conjunction with the motor B, provides a very simple, mechanically and readily operable arrangement. The tapered portions 84 and 85 are each exposed to the hydraulic fluid pressure in the chamber 75 which provides a balancing arrangement so that when the valve member '79 is moved to the left, it can do so easily and without requiring a force to overcome the hydraulic pressure. Furthermore, the line of movement of the valve member 79 is parallel to the axis of the shaft 14 so that the valve member itself may, by being physically extended, cooperate with the bell crank lever 66 in a positive and simple manner to enable the cooperative and synchronized operation described above.

The fluid-translating device described above is simply illustrative of my invention and, obviously, other modifications and alterations will occur to others upon a reading and understanding of this specification, such modifications and alterations, even though differing radically in appearance from that shown, come within the scope of the present invention insofar as they are covered by the appended claims.

Having thus described my invention, I claim:

1. A hydraulic starting motor comprising a body member, a shaft rotatably supported in said housing member, a hydraulic motor in said housing for rotating said shaft, a pinion member slidable on said shaft and rotatable therewith adapted to be engaged with a driven gear, said gear normally being in axially spaced relationship, a member for advancing said pinion into engagement with said driven gear, valve mechanism in said body member, said valve mechanism including an outlet chamber communicating with said hydraulic motor and an inlet chamber communicating with a source of hydraulic pressure, and a Wall having an opening therein intercommunicating said chambers, a valve member reciprocable in said opening and having a portion of gradually reducing diameter from both ends of a length longer than the length of said opening whereby said chambers will be gradually intercommunicated as said reduced portion is moved into said opening, means interconnecting said valve member with said member for actuating said pinion, said valve member requiring a greater distance of movement to intercommunicate said passages than the distances required to intermesh said gears and gradually admitting more hydraulic fluid to said motor as said gears are intermeshed.

2. A hydraulic starting motor comprising a housing member, a shaft rotatably supported in said housing member, a hydraulic motor for forceably rotating said shaft, a pinion slidably mounted on said shaft for rotation therewith, a driven gear axially spaced from said pinion and adapted to be engaged thereby upon sliding movement of said pinion on said shaft, a member for sliding said pinion on said shaft into engagement with said driven gear, valve means integral with said housing for admitting hydraulic fiuid to said motor, said valve means including an inlet chamber adapted to communicate with a source of high-pressure fluid and an outlet chamber adapted to communicate with said motor, and an intercommunicating passage between said chambers, a valve member having a portion of gradually reducing dimensions from both ends slidable in said passage, said valve member upon movement adapted, in one position, to gradually intercommunicate said inlet and outlet chambers, and, in another position, to prevent the flow of fluid therebetween, means interconnecting said valve member with means for sliding said pinion into engagement with said driven gear, said valve member and means being so constructed and arranged that said valve member is gradually opened as said pinion is gradually engaged with said driven gear, whereby the torque developed by said motor will generally be proportional to the amount of engagement of said gears.

3. A hydraulic starting motor comprising a body memher, a shaft rotatably supported in said housing member, a hydraulic motor in said housing for rotating said shaft, a pinion member slidable on said shaft and rotatable therewith adapted to be engaged with a driven gear, said gear normally being in axially spaced relationship, a member for advancing said pinion into engagement with said driven gear, valve mechanism in said body member, said valve mechanism including an outlet chamber communicating with said hydraulic motor and an inlet chamber communicating with a source of hydraulic pressure, a valve member adapted upon movement to intercommunicate said chambers, means interconnecting said valve member with said member for actuating said pinion, said valve member requiring a greater distance of movement to intercommunicate said passages than the distances required to intermesh said gears and gradually admitting more hydraulic fluid to said motor as said gears are intermeshed.

4. A hydraulic starting motor comprising a housing member, a shaft rotatably supported in said housing member, a hydraulic motor for forceably rotating said shaft, a pinion slidably mounted on said shaft for rotation therewith, a driven gear axially spaced from said pinion and adapted to be engaged thereby upon sliding movement of said pinion on said shaft, a member for sliding said pinion on said shaft into engagement with said driven gear, valve means for admitting hydraulic fluid to said motor, said valve means including an inlet chamber adapted to communicate with a source of high-pressure fluid and an outlet chamber adapted to communicate with said motor, an intercommunicating passage between said chambers, a valve member slidable in said passage, said valve member upon movement being adapted, in one position, to gradually intercommunicate said inlet and outlet chambers and, in another position, to prevent the flow of fluid therebetween, means interconnecting said valve mcmber with means for sliding said pinion into engagement with said driven gear, said valve member and means being so constructed and arranged that said valve member is gradually opened as said pinion is gradually engaged with said driven gear, whereby the torque developed by said motor Will generally be proportional to the amount of engagement of said gears.

57 A hydraulic starting motor comprising a body member, a shaft rotatably supported in said housing member, a hydraulic motor in said housing for rotating said shaft, a pinion member slidable on said shaft and rotatable therewith adapted to be engaged with a driven gear, said gear normally being in axially spaced relationship, a member for advancing said pinion into engagement with said driven gear, valve mechanism in said body member, said valve mechanism including an outlet chamber communicating with said hydraulic motor and an inlet chamber communicating with a source of hydraulic pressure, a manually operable valve member adapted upon movement to intercommunicate said chambers, means interconnecting said valve member with said member for actuating said pinion, said valve member requiring a greater distance of movement to intercommunicate said passages than the distances required to intermesh said gears and gradually admitting more hydraulic fluid to said motor as said gears are intermeshed.

6. A hydraulic starting motor comprising a housing member, a shaft rotatably supported in said housing member, a hydraulic motor for forceably rotating said shaft, a pinion slidably mounted on said shaft for rotation therewith, a driven gear axially spaced from said pinion and adapted to be engaged thereby upon sliding movement of said pinion on said shaft, a member for sliding said pinion on said shaft into engagement with said driven gear, valve means for admitting hydraulic fluid to said motor, said valve means including an inlet chamber adapted to communicate with a source of highpressure fluid and an outlet chamber adapted to communicate with said motor, an intercommunicating passage between said chambers, a manually operable valve member slidable in said passage, said valve member upon movement being adapted, in one position, to gradually intercommunicate said inlet and outlet chambers and, in another position, to prevent the fiow of fluid therebetween, means interconnecting said valve member with means for sliding said pinion into engagement with said driven gear, said valve member and means being so constructed and arranged that said valve member is gradually opened as said pinion is gradually engaged with said driven gear, whereby the torque developed by said motor will generally be proportional to the amount of engagement of said gears.

References Cited in the file of this patent UNITED STATES PATENTS 867,119 Forsyth Sept. 24, 1907 1,800,929 Craig Apr. 14, 1931 1,945,391 Benedick Jan. 30, 1934 1,970,133 Ferris et a1 Aug. 14, 1934 2,069,364 Gussick Feb. 2, 1937 2,229,715 Zimmerman Jan. 28, 1941 2,347,351 Laing Apr. 25, 1944 2,424,035 Ifield July 15, 1947 2,467,067 Wilson Apr. 12, 1949 2,506,663 DeGuerin May 9, 1950 2,633,104 Lauck et a1 Mar. 31, 1953 

